Automatic bead release device for tyre removal machines, and tyre removal machines equipped therewith

ABSTRACT

An automatic bead release device for tire removal machines, comprising, for supporting the wheel rim complete with tire, rotary means associated with a frame which supports a bead release disc in contact with the tire just external to the flange of the wheel rim, a shaft parallel to its axis of rotation, on which said frame slides to approach and withdraw from the wheel rim, means for moving said frame along said shaft, and means for lightly inserting said disc below the flange of the wheel rim after it has come into contact with it.

[0001] This invention concerns bead release devices used for detachingthe tire bead from the bead retaining flange of the wheel rim.

[0002] The known art teaches that to remove a tire from the wheel rimthe first operation to be carried out is to detach the tire bead fromthe bead retaining flange of the wheel rim. Said operation is effectedby devices, known as bead release tools, usually installed on tireremoval machines.

[0003] Said devices are generally positioned to the side of the machinecasing, and comprise a horizontal arm, one end of which is hinged tosaid base on a vertical axis, its opposite end carrying a bead releasetool in the form of a curved blade.

[0004] Said arm is associated with a pad mounted on said casing, againstwhich the wheel, comprising the wheel rim and tire, rests during thebead release ope.ation.

[0005] Between the arm and the casing there is interposed a pneumaticcylinder-piston unit, provided to move said arm towards the machinecasing in order to accomplish the bead release.

[0006] Although devices of this type satisfy their purpose, they presentcertain drawbacks.

[0007] Firstly, they operate on the wheel while at rest, and involveonly a sector of the tire edge at a time.

[0008] In addition, as the operator has to maintain the wheel at restduring tire release, he finds himself relatively close to the region inwhich the tool operates, and is consequently subject to the risk ofaccidents.

[0009] A further drawback is the physical force which the operator hasto apply to maintain the wheel at rest during bead release, and torotate it to repeat the operation along different sectors of the tireedge.

[0010] Finally, with bead release devices of known type the operator iscompelled to turn the wheel over at least once through 180° about adiametrical axis to be able to carry out the operation along both edgesof the tire, hence increasing the time required for the operation.

[0011] The object of the present invention is to overcome the drawbacksof the known art within the framework of a rational and reliablesolution which enables the operator to dispense with the need tointervene actively during the operation.

[0012] The invention attains said object by virtue of a bead releasedevice which, associated with rotary support means for the completewheel rim of the tire, acts on at least one side thereof while rotating,without any intervention by the operator.

[0013] According to the invention the device is associated with meansfor positioning the flange of the wheel rim in a fixed position relativeto the tool of the bead release device, by virtue of the fact that thewheel rim support device can translate parallel to itself towards andaway from the bead release device, or vice versa.

[0014] Preferably the bead release device is fixed in position, whereasthe wheel rim support means move towards and away from it.

[0015] Moreover, the wheel rim support means are preferably such as toleave both flanges of the wheel rim free, so that the bead releasedevice can act simultaneously on both.

[0016] Finally, the combination of the bead release device with saidrotary support means for the wheel rim results in an assembly which canbe easily provided with tools, of known type, for mounting and/orremoving the tire bead onto or from the flange of the wheel rim, soresulting in a complete tire removal machine.

[0017] The particular characteristics of the invention are defined inthe claims.

[0018] The constructional and operational characteristics will be moreapparent from the ensuing description of a preferred embodiment thereofgiven by way of non-limiting example and illustrated in the accompanyingdrawings.

[0019]FIG. 1 is a perspective view of the invention.

[0020]FIG. 2 is a side view of FIG. 1.

[0021]FIG. 3 is a section on the line III-III of FIG. 2.

[0022]FIG. 4 is a partially interrupted view of the bead release deviceused by the invention.

[0023]FIG. 5 is a vertical section through FIG. 4.

[0024] The ensuing description, with reference as stated to saidfigures, concerns for economy of description a complete tire removalmachine, but without this limiting the protection of the patent to thecombination of all the means described.

[0025] Said figures show the tire removal machine 1, which comprises alower base 2, from the upper surface of which there projects a shell 3containing a vertical shaft 16 carrying the means 4 for supporting andlocking in position the wheel 5, inclusive of the wheel rim 6 and tire7, as shown in FIG. 2.

[0026] To the base 2 there is fixed a vertical column 8 carrying boththe support and positioning means for the usual tire mounting andremoval tool 14, known per se, and the bead release device 15 with whichthe invention is provided.

[0027] The shaft 16 is a rotary shaft supported by a lower movingassembly, not shown, which can translate horizontally within thevertical plane comprising the axis of the tool 14.

[0028] With reference to FIG. 3, the means 4 for locking the wheel rim 6comprise a hollow upper-end portion of the shaft 16 with its internalcavity of hexagonal cross-section, to the upper end of which there isfixed a circular plate 17 on which the wheel rim 6 is rested.

[0029] The plate 17 is provided with upper radial grooves 172 and with alower cylindrical skirt 170, to the free end of which there is fixed acover 18 which, together with said skirt, defines a chamber 19.

[0030] Within the skirt 170 there slides an annular piston 20 providedwith a hollow rod 200 sealedly mounted about the shaft 16.

[0031] Within the wall of the hollow rod 200 there is present a conduit201 which feeds compressed air onto the piston 20.

[0032] Between said piston 20 and said cover 18 there is interposed acompressed spring 21.

[0033] The rod 200 of the piston 20 supports an external U-shaped pawl22 which embraces the rod and comprises a central tooth 220. The pawlrocks about two projecting pins 23 positioned on the same diametricalaxis, and is provided with a tooth 220 which enters into the interior ofsaid hollow shaft 16 via apertures 202 and 160.

[0034] The interior of said hollow shaft 16 receives the bar 240, alsoof hexagonal cross-section, of a device 24 provided for locking thewheel rim 6 in the working position.

[0035] Said device 24 comprises said bar 240, which is fixed to an uppermember 241 to which there is also fixed a locking cone 242, which ismounted about the bar 240.

[0036] The member 241 also comprises an internally hollow handle 243within which there slides a bar 244, the free end of which carries avertical sleeve 245 within which a second bar 246 slides. When the wheelrim 6 is in the working position, the bar 240 is inserted into thehollow shaft 16, and said second bar 246 is positioned in one of theholes 60 intended to receive the bolts by which the wheel rim is fixedto the vehicle.

[0037] The hexagonal cross-section of the bar 240 ensures that when thedevice 24 is inserted, the lower end of the bar 246 always encountersand becomes inserted in one of the radial grooves 172 present in thecircular plate 17.

[0038] The bar 240 comprises annular projections 250 which are upperlyflat and lowerly conical, so that when the bar is inserted into thehollow shaft 16 the conical part of the projections causes the pawl 22to rotate against the action of a leaf spring 25, while at the same timethe bar is unable to be withdrawn because the leaf spring maintains thepawl 22 above the upper flat surface of said projections 250.

[0039] The bar 240 is inserted into the hollow shaft 16 until the cone242 encounters the outer surface of the central hub 61 of the wheel rim6. At this point by feeding compressed air through the conduit 201 thepiston 20 descends against the action of the spring 21. The descent ofthe piston also determines the lowering of the pawl 22, the tooth 220 ofwhich rests against the flat upper surface of the annular projections250, and remains locked in position by the action exerted by the leafspring 25. In this manner, the wheel rim 6 becomes locked in the workingposition.

[0040] The wheel rim is released by simply releasing the compressed airfrom the operating chamber 19. In this manner, the spring 21 causes thepiston 20 and the pawl 22 to rise, this latter, by its rotation,disengaging from the annular projection 250.

[0041] As shown in FIGS. 4 and 5, the bead release device comprises avertical shaft 27, of square or otherwise non-circular cross-section,supported between the plates 80 and 81, which are rigid with the column8 and with the machine base respectively.

[0042] The shaft 27 can rotate about its axis, being driven by anactuator, not shown but of known type.

[0043] On said shaft 27 there slide two units 28 and 30, driven bycylinder-piston units 281 and 301 respectively.

[0044] The upper unit 28 comprises a frame 282 having a lateral plate283 from which there branch two blocks 284 provided with axial holeswithin which there slides a bar 285 of non-circular cross-section.

[0045] At one end, the bar 285 rotatably carries the bead release disc286, which is idle about its axis 296 and is maintained in position by aspring, its rotation being measured by the feeler 287.

[0046] The bar is maintained urged inwards (towards the left in FIG. 5)by the spring 288 and carries at its opposite end a roller 289 whichrests against a profiled block 290, above a projecting cam 291.

[0047] The profiled block 290 is slidable on the shaft 27 and maintainedresting against the frame 28 by the spring 292, and can be locked on theshaft 27 by the strangling plate 293 rotated by the air piston 294.

[0048] The air piston 294 is controlled by the feeler 287, whichmeasures the rotation of the bead release disc 286 when this restsagainst the tire bead.

[0049] The unit 30 is identical to the unit 28, and is disposed invertedthereto at the lower end of the shaft 27.

[0050] The components of the unit 30 are identified by the numbers from301 to 316, corresponding to the numbers from 281 to 296 of thecorresponding components of the unit 28.

[0051] The units 28 and 30 are maintained at their respective ends ofthe shaft 27 by the cylinder-piston units 281 and 301 respectively.

[0052] With reference to FIGS. 1 and 2, the support and positioningmeans 11 for the usual tool 14 comprise a horizontal guide sleeve 9,which is fixed to the plate 80 rigid with the column 8, and to theinterior of which the profiled bar 10 is fixed. It should be noted thatthe horizontal axis of the bar 10 intersects the central vertical axisof said means 4 for supporting the wheel 5 and locking it in position.

[0053] At the end of said profiled bar 10 there is supported a guide ofvertical axis, which receives and can lock a rod 13, to the lower end ofwhich there is connected the usual tool 14 which interacts with the beadof the tire 7.

[0054] A programmed electronic processor unit coordinates the movementof certain of the aforedescribed devices as will be apparenthereinafter.

[0055] The aforedescribed devices operate in the following manner.

[0056] The operator places the wheel rim 6 complete with tire 7 on theplate 17 in an approximately centered position.

[0057] He then inserts the bar 240 of the locking means 4 into thecavity of the shaft 16 until the conical member 242 centres the centralhole of the wheel rim; at the same time he inserts the locking bar 246though one of the wheel rim holes intended to receive the fixing bolts,taking care that the end of the locking bar enters one of the grooves172 in the plate 17.

[0058] In this manner the locking bar is arranged to rotate the wheelrim, which remains secured both upperly and lowerly.

[0059] After these operations, the operator feeds compressed air intothe chamber 19, causing the piston 20 to descend and properly lock theassembly.

[0060] At this point the operator feeds the wheel rim dimensions to theprocessor, which then causes the shaft 16 to translate until it reachesa zero position in which the bead release discs 286 and 306 lie justoutside the flange on the wheel rim.

[0061] Simultaneously, the processor causes the shaft 27 to rotate suchthat the axes 296 and 316 of rotation of the bead release discs 286 and306 cut the axis of the shaft 16.

[0062] The machine is thus ready to release the bead and possibly removethe tire in a completely automatic manner.

[0063] The operator has only to feed compressed air to the twocylinder-piston units 281 and 301, which cause the units 28 and 30 toapproach the wheel from both sides of it.

[0064] The operation of only the unit 28 will now be described as theoperation of the unit 30 is identical.

[0065] When the disc 286 comes into contact with the sidewall of thetire in the immediate vicinity of the wheel rim flange, it rotatesslightly upwards to operate the feeler 287.

[0066] This latter causes the cylinder-piston unit 294 to incline thestrangling plate 293, which hence locks the block 290 to the shaft 27.

[0067] As the frame 28 continues to descend downwards, the rear roller289 of the profiled bar 285 rises along the cam 291 to compel the bar toslide slightly forwards to insert the disc 286 slightly below the wheelrim flange, and act exactly on the wheel tire.

[0068] The piston 281 acts as an air spring, so maintaining the disc 286pressed downwards with the necessary force, the rotation of the wheelcausing it to act along the entire length of the bead, to remove thislatter perfectly from the wheel rim flange.

[0069] When the bead has been detached, the tire is removed in thenormal manner by the tool 14, which is lowered manually into positionand locked with usual means by the operator.

1. An automatic bead release device for tire removal machines,characterised by comprising, for supporting the wheel rim complete withtire, rotary means associated with a frame which supports a bead releasedisc in contact with the tire just external to the flange of the wheelrim, a shaft parallel to its axis of rotation, on which said frameslides to approach and withdraw from the wheel rim, means for movingsaid frame along said shaft, and means for lightly inserting said discbelow the flange of the wheel rim after it has come into contact withit.
 2. A device as claimed in claim 1 , characterised in that said discis positioned at the end of a bar perpendicular to said shaft andaxially slidable within guides present on said frame, the other end ofsaid bar being provided with a roller arranged to slide along a camnormally rigid with the frame, and arranged to be locked to the shaftwhen the disc comes into contact with the tire.
 3. A device as claimedin claim 1 , characterised in that said cam is provided on a blockslidable on the shaft and connected to the frame by elastic means,strangling means being provided to lock the block to the shaft.
 4. Adevice as claimed in claim 1 , characterised in that said shaft isassociated with means which cause it to rotate on command, to positionthe axis such that it cuts the axis of rotation of the wheel rim.
 5. Adevice as claimed in claim 1 , characterised in that the means formoving the frame along the shaft are a pneumatic cylinder-piston unit.6. A device as claimed in the preceding claims, characterised bycomprising two frames symmetrically disposed on the same shaft, insymmetrically facing positions.
 7. A device as claimed in claim 1 ,characterised in that said rotary means for supporting the wheel rim areslidable in a horizontal direction, in order to be positioned at thedesired distance from said bead release disc.
 8. A device as claimed inclaim 7 , characterised in that said rotary means for supporting thewheel rim comprise a rotary hollow shaft provided with an upper plate, apawl means insertable laterally into the interior of said hollow shaft,a bar provided with circumferential teeth and insertable into saidshaft, within which said teeth engage said pawl, and carrying at its topa centering and locking cone for the wheel rim, and means for causingsaid pawl to move axially to said shaft, to lock said cone against saidwheel rim.
 9. A device as claimed in claim 8 , characterised in that theupper plate is provided with radial grooves, in one of which thereengages the lower end of a locking bar slidable within a seat rigid withthe centering cone.
 10. A device as claimed in claim 8 , characterisedin that the upper plate of the rotary shaft comprises a descendingcylindrical skirt within which there sealedly slides a piston providedwith a hollow rod positioned externally to the shaft, said hollow rodbeing provided with an aperture through which said pawl acts, in aposition corresponding with this aperture there being located in thewall of the hollow shaft an opening through which said pawl comes intocontact with the teeth of the bar carrying the centering cone.
 11. Adevice as claimed in claim 10 , characterised in that the conduit whichfeeds compressed air onto the piston is provided within the wall of thehollow rod of the piston.
 12. A tire removal machine comprising a basefrom which there upwardly project rotary means for supporting the wheelrim, and a column carrying at least one tool arranged to interact withthe tire bead, characterised in that said tool undergoes movementsparallel to the axis of rotation of the wheel rim, and the rotary meanssupporting the wheel rim undergo translating movements arranged toposition the flange of the wheel rim in a fixed zero position relativeto the direction of movement of said tool.
 13. A machine as claimed inclaim 12 , characterised in that said at least one tool is a tireremoval tool.
 14. A machine as claimed in claim 12 , characterised inthat said at least one tool is a bead release tool.
 15. A machine asclaimed in claim 12 , characterised in that said bead release tool is inthe form of a disc and is supported by a frame slidable on a shaftparallel to the axis of rotation of the wheel rim.
 16. A machine asclaimed in claim 15 , characterised by comprising at least two beadrelease tools supported by two frames slidable on the same shaft.
 17. Amachine as claimed in claim 15 , characterised in that the shaft canrotate about its axis in order to position the axis of the bead releasedisc such that it cuts the axis of rotation of the wheel rim.